title: Solvent-mediated pseudo-quadruple hydrogen-bond motifs in three lamotrigine-carboxylic acid complexes.
abstract: Lamotrigine, an antiepileptic drug, has been complexed with three aromatic carboxylic acids. All three compounds crystallize with the inclusion of N,N-dimethylformamide (DMF) solvent, viz. lamotriginium [3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium] 4-iodobenzoate N,N-dimethylformamide monosolvate, C9H8Cl2N5(+)·C7H4IO2(-)·C3H7NO, (I), lamotriginium 4-methylbenzoate N,N-dimethylformamide monosolvate, C9H7Cl2N5(+)·C8H8O2(-)·C3H7NO, (II), and lamotriginium 3,5-dinitro-2-hydroxybenzoate N,N-dimethylformamide monosolvate, C9H8Cl2N5(+)·C7H3N2O7(-)·C3H7NO, (III). In all three structures, proton transfer takes place from the acid to the lamotrigine molecule. However, in (I) and (II), the acidic H atom is disordered over two sites and there is only partial transfer of the H atom from O to N. In (III), the corresponding H atom is ordered and complete proton transfer has occurred. Lamotrigine-lamotrigine, lamotrigine-acid and lamotrigine-solvent interactions are observed in all three structures and they thereby exhibit isostructurality. The DMF solvent extends the lamotrigine-lamotrigine dimers into a pseudo-quadruple hydrogen-bonding motif.
authors.affiliation: X-ray Crystallography Division, CSIR - Indian Institute of Chemical Technology, Hyderabad 500 007, India.
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Sridhar
authors.forename: Jagadeesh Babu
authors.initials: JB
authors.lastname: Nanubolu
authors.forename: Krishnan
authors.initials: K
authors.lastname: Ravikumar
mesh_terms: D000927:Anticonvulsants / Q000737:chemistry* / Q000494:pharmacology; D002264:Carboxylic Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D000077213:Lamotrigine; D015394:Molecular Structure; D012997:Solvents / Q000737:chemistry*; D014227:Triazines / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000927:Anticonvulsants; D002264:Carboxylic Acids; D012997:Solvents; D014227:Triazines; D000077213:Lamotrigine
keywords: active pharmaceutical ingredients; anticonvulsants; antiepilepsy drugs; crystal structure; hydrogen bonding; isostructurality; solvated lamotrigine salts